My daughter lost the keyless entry fob to her sentra about a month ago. she now just uses the key to lock the doors. all is well with that. But last night at 3:00 am the alarm/ horn and light went off for no reason at all. woke up my neighbors. How can I disarm alarm so this won't happen again. (I was able to unlock the drivers door and start the car, and the alarm went off. but I left the car unlocked)